Slice onion and place 3/4 of it in the bottom of the crock pot. Sprinkle roast with garlic powder and garlic powder granules and then place roast on top of onion; add remaining onion on top of the roast. Sprinkle soup mix and beef stew seasoning mix on top and around the roast. Pour 1 cup water over roast and then cook on high about 4 to 5 hours until meat is fork tender.